Magnesium based casting alloys have been utilized extensively in the automotive industry to reduce component weight while providing structural rigidity. As an example, magnesium based alloys have been used to produce transfer cases, transmission cases, oil pans, front engine covers, engine blocks, cam covers, valve covers and cylinder heads.
One drawback associated with some magnesium based alloys is known as creep. Creep occurs when a material continues to deform under constant stress and temperature. Creep resistance is a desirable characteristic for use of magnesium based alloys in power train components. Creep resistance under compressive load and temperature is necessary in order to maintain bolt torque and dimensional stability of cast bodies during vehicle operation. However, known magnesium alloys exhibiting good creep resistance exhibit poor castability and vice versa. Poor castability is indicative of die sticking, oxidation and deficient fluidity and may result in higher production costs during mass production using permanent mold castings.
Yet another drawback to some magnesium based alloys is the conventionally required addition of beryllium to prevent oxidation of the melt.
What is needed therefore, is a magnesium based alloy with both improved creep resistance and castability that does not require the addition of beryllium.